数学简便计算题 快(1/5+1/7+1/9)+(1/7+1/9+1/11)+(1/7+1/9)*(1/5+1/7+1/9+1/11)简便计算

问题描述:

数学简便计算题 快
(1/5+1/7+1/9)+(1/7+1/9+1/11)+(1/7+1/9)*(1/5+1/7+1/9+1/11)
简便计算